The present invention relates to an oscillation gyroscope, and in particular to an oscillation gyroscope which is used in navigation systems, shaking prevention systems and the like, for example. FIG. 9 is a cutaway perspective view showing an example of a conventional oscillation gyroscope 100 which is the background of this invention, and FIG. 10 is a circuit drawing of the oscillation gyroscope 100. This oscillation gyroscope 100 includes an oscillator 102. The oscillator 102 includes a cross-sectional triangular oscillating body 103, and piezoelectric elements 104a, 104b and 104c which are formed in the three side surfaces of the oscillating body 103, as shown in FIG. 10. Each of these piezoelectric elements 104a to 104c form electrodes on both surfaces of a piezo ceramics for example.
As shown in FIG. 9, the oscillator 102 has support members 105a and 105b which are substantially C-shaped and are each attached to ridge line portions in the vicinity of two node points. The end portions of these support members 105a and 105b are respectively fixed to a flat plate shaped attachment boards 106a and 106b. The attachment boards 106a and 106b are separated into two so as not to suppress the vibration of the oscillator 102. Also, a plurality of terminal electrodes (not shown in the drawing) are formed on the attachment board 106a, and these are respectively electrically connected with the electrodes of the piezoelectric elements 104a to 104c of the oscillator 102 via lead wires. Further, on the attachment boards 106a and 106b, substantially C-shaped protective plates 110a and 110b are fixed substantially perpendicular to the main surfaces of the attachment boards 106a and 106b by attaching them by soldering or welding. The protective plates 110a and 110b have respective predetermined gaps from the lower surface of the oscillator 102, which are for the purpose of protecting the support members 105a and 105b so that the oscillator 102 is not displaced more than necessary when shocks are imposed thereon.
The attachment boards 106a and 106b are each fixed to one main surface of a cross-sectional substantially C-shaped metal frame 107. The metal frame 107 is fixed to one main surface of a flat plate-shaped circuit board 108. An oscillator circuit 113 comprising chip components such as an operational amplifier, resistors, capacitors, etc., a variable resistor unit etc., and a detection circuit 114, and the like are mounted on the other main surface of the circuit board 108. Also, the attachment board 106a and the circuit board 108 are rigidly coupled to each other by rigid metal terminals 109a to 109d comprising metal plates which are substantially L-shaped and have predetermined widths and lengths. The end portions of each of the rigid metal terminals 109a to 109d are each rigidly fixed to the attachment board 106a and the circuit board 108, respectively. Also, the terminal electrodes on the attachment boards 106a and 106b are connected to the terminal electrodes (not shown in the drawing) of the circuit board 108 via the rigid metal terminals 109a to 109d, respectively. Further, as shown in FIG. 9, the oscillator 102, the metal frame 107, the rigid metal terminals 109a to 109d, etc. are all housed in a box-shaped case 112. In addition, both ends in the length direction of the oscillator 102 are protected by the inside surface of the case 112 so that the oscillator 102 is not displaced more than necessary when shocks are imposed thereon.
As shown in FIG. 10, one piezoelectric element 104c of the oscillator 102 is electrically connected to an input terminal of the oscillator circuit 113, and an output terminal of the oscillator circuit 113 is electrically connected to the other two piezoelectric elements 104a and 104b, respectively. As a result, the oscillator 102 is driven by self-excitation. Also, the two piezoelectric elements 104a and 104b are each electrically connected to input terminals of the detection circuit 114 comprising a differential amplifier, for example. Accordingly, rotation angle velocity is detected by the output circuit of the detection circuit 114.
However, if the spaces between the oscillator 102 and the case 112 surrounding it and the protective plates 110a and 110b is too short, the vibration of the oscillator 102 is hindered, and if the spaces are too long, the oscillator 102 is greatly displaced when a shock is imposed causing the support members 105a and 105b to be plastically deformed. As a result, there is a possibility that the oscillation gyroscope 100 may cease to function. Therefore, these spaces must be precisely formed to a length which does not hinder the vibration of the oscillator 102 and which does not cause plastic deformation of the support members 105a and 105b.
However, because in the oscillation gyroscope 100 of the prior art, the protective plates 110a and 110b are affixed by soldering or the like, the space between the protective plates 110a and 110b and the oscillator 102 may fluctuate readily depending on the amount of solder or the like. Further, the space between the protective plates 110a and 110b and the oscillator 102 may fluctuate readily in the period until the solder or the like hardens.
In addition, because the metal terminals 109a to 109d are provided at only one location in the lengthwise direction of the oscillator 102, when the case 112 is attached, the space between the case 112 and the oscillator 102 may vary readily at both sides in the lengthwise direction of the oscillator 102. Further, in the prior art oscillator gyroscope 100, the upper end in the height direction of the oscillator 102 is protected by the case 112, but it is difficult to form the space between the case 112 and the oscillator 102 precisely.
In this way, in the oscillation gyroscope 100 of the prior art, because it is difficult to precisely form the space between the oscillator 102 and the periphery thereof, it is also difficult to improve the shock resistance thereof. Also, in the oscillation gyroscope 100 shown in FIG. 9, displacement in both diagonal upward directions of the oscillator 102 cannot be sufficiently prevented, and when a large shock is imposed in these directions, the shock resistance has not been found to be sufficient.